Electrical connector



Aug 24, 1965 s. BosWoRTl-l ETAL 3,202,953

ELECTRICAL CONNECTOR 2 Sheets-Sheet 1 FIG.

Filed Jan. '7, 196s F IG. 1

FIG. 3

IHHIUIHII ssf FIG.

lNvENToRS SEYMOUR BoswoRTH JEROME ZAUDERER 60. fb. @ML

ATTORNEY Allg- 24, 1965 s. BoswoRTx-x ETAL ELECTRICAL CONNECTOR 2 Sheets-Sheet 2 Filed Jan. 7, 1963 1N VENTORS FIG HR mm OE Y WD E SU N OA BZ H R 0M@ MO YR EE SJ FIG. 6

United StatesN Patent O 3,262,953 ELECTRICAL CNNEC'IIOIR-` Seymour Bosworth, Plainview, and Jerome Zanden-er, Brooklyn, NX., assignors to Abbey Electronics Corp., Long Island, NX., a corporation otNew York Filed Jan. 7, 1963, Ser. No. 249,639 3 Claims. (Cl. 339-42) This invention relates to the art of electrical connectors and more particularly concerns an electric plug for connection of an electric cable to a jack, socket or receptacle.

When electric cables or cords carry high voltage it is desirable that the plugs used to connect them to appropn'ate electric circuits avoid exposing the high voltagepins or prongs of the plug to contact by operating personnel or to contact with various parts of the circuits. Heretofore substantially all plugs used for test leads` in meters and for electric connections of various other types have all had exposed projecting studs, prongs or pins.

The present invention has as a principal object to provide a plug which has a prong, conducting portions of which are always concealed within a housing of the plug.

A further object is to provide a plug which has a fixed axial pin or prong surrounded by a spring loaded retractable non-conductive shell, the shell being movable axially of the pin to permit the pin to be inserted into a jack, socket or receptacle of a circuit.

A further object is to provide a plug of the character described, wherein the pin' or prong has a non-conductive tip for separating and engaging spring contacts of a jack, socket or receptacle, while other portionsV 'of the pin or prong are electricallyV conductive for contacting appropriate conductive parts of the jack.

Another object is to provide a plug of the character described, where a plurality of nterfitted partsV are provided which are so arranged that the prong or pin is disposed and held axially of the surrounding shell.

A still further object is to` provide a plug of the character described which is made of parts which can be quickly assembled and disassembled, and which is durable and foolproof in operation.

The invention will be est understood from the following detailed description taken together withI the drawing wherein:

FIG. 1 is a side elevational view of a plug embodying the invention.

FIG. 2 is a bottom plan view of the plug.

FIG. 3 is a side elevational View of -a plug on an enlarged scale, shown mounted on panel and engaged with an associated jack.

FIG. 4 is a vertical central sectional View through the plug and jack of FIG. 3.

FIG. 5 is an exploded perspective view of a plug embodying the invention.

FIG. 6 is a vertical sectional view similar to part of FIG. 3, of another plug.

FIG. 7 is a transverse sectional view taken on line 7-7 of FIG. 6. y

FIG. 8 is a sectional view similar to a part of FIG. 6, showing another plug construction.

FIG. 9 is a vertical sectional view similar to parts of FIG. 4, showing the plug construction of FIG. 8 in association with a panel and jack.

Referring first to FIGS. 1-3, there is shown a plug 10 embodying the invention. This plug has a cylindrical body 11 having a cylindrical head 12 at one end where an electric cord or cable 14 enters the dat top of the head into the plug. The plug has pin 16 fixed axially 3,2%?,953 Patented Aug. 24, 1965 therein and extending outwardly of body 11 oppositely 'o head 12. Surrounding the pin and concentric therewitl is a hollow, retractable shell .13 extending outwardly o body 11 and movable partially into the body axiall thereof. The pin 16 has a non-conductive cylindrica tip 20 formed with knob 22 defined by a circumferentia groove 24. This tip is exposed when the shell is fully extended as shown in FIG. 1.

FIGS. 4 and 5 show details of internal parts and con struction of plug 10. Body 11 has an external threat 26 at its upper end which engages with internal threat 2S of head 12. The head is hollow and includes a a top 15 provided with a hole 30 through which passe; electric cord 14. A cylindrical or tubular insulated it ting 32 is provided inside the head and body of the plug This fitting has an annular ange 34 formed at its uppei end. This flange seats 'on top of an annular interna ange 36formed in a ring 3S. The ring is tightly en gaged between the upper end of body 11 and the under side of top 15 when the head is tightened on the body The fitting 32 extends axially downward through the ring andis coaxial with and inside the body. The tting ha; an enlarged internal threaded tubular portion 4@ at th lower end of its central bore 42 to receive a threadec head 44 formed at the end of a conductive metal tube 46 Tube 46 forms part of pin or prong 16. The tube has a1 internal thread 48 at its lower end to receive and en gage a threaded stud S0 formed at the upper end of til 2i). The tube has an axial bore in which terminates tht wire 17 of cord 14. The wire may be secured to the tube 46 or to its head 44 by solder 52 or by other suit able means to insure electrical continuity between tht wire and tube. A coil spring 49 concentric with ittinl 32 is located between the top of shell 18 and the under side 'of flange 36.

All parts of the plug except the metal tube and spring are preferably made of plastic non-conductive, insula tion material. The tip 2i) of the pin is preferably made of so-called self-lubricating plastic, such as nylon, poly tetrauorethylene or the like. Y

It will be noted that shell 18 has an external annulai ange 19 at its upper end which diameter is substantially equal to the internal diameter of body 11. Body 11 ha: an internal circumferential ange 21 at its bottom ent which is aligned with flange 19 to prevent the shell fron becoming detached from the body.

The spring 4% tends to expand and Ibias the shell outwardly of the body. The axial length of the shell i: greater than the axial length of the portion of tube 4t which extendsV outwardly of body 11. Thus the shel conceals the tube when the shell is in its fully extendeC position shown in FIGS. l and 4.

FIGS. 3 and 4 show a non-conductive panel 54 upor which plug 1G is mounted in operative position. The panel may have a hole 56 through which pin 16 may be passed. A jack 55 is shown mounted on another pane 58 rigidly carried on a suitable support not shown. Thif support may be the panel 54. The jack has a first pair of outer spring contacts 6l) opposing each other at flexible ends beyond panel 5S. The ends of the contacts have outwardly ilared lingers 64. A second pair of conductive spring contacts 66 are disposed respectively between the contacts 60 and panel 56. A third pair of spring contacts 68 are respectively disposed between contacts 60 and 66 Insulation strips 61 are disposed between contacts 60 anc 68. Insulation strips 63 are disposed between contacte 66 and 68. Non-conductive, plastic screws 69 are inserted through registering holes in the several contacts, strips and panel 58, and are secured by metal or plastic nuts 70. The several contacts have bent ends 72 to which suitable ectric connections may bc made from an electric cirlit or circuits carried by panel 53 or some other support.

In operation of the plug, the bottom end of shell 1S ill be placed against the outer surface of panel 54 with )n-conductive tip 2@ extending through hole 56. First p 2t) will engage and separate fingers 64 of contacts 69. s the plug is pushed axially downward toward jack 55, le shell f8 will retract against increasing tension in spring l* while tip 2f? will advance into engagement with con- ,cts 66. The rounded knob of the tip will separate the )ntacts 66 and the bent ends 66' of the contacts will igage at groove 24 to retain knob 22. At the same time le metal tubular portion 46 of the pin i6 will reach and )ntact both contact fingers 64 to complete an electric rcuit between wire 17 and both fingers 64. When the )ntacts 66 are separated they bear against the contact .ements 68 which serve to back up the contacts 65 and iaintain a rmer spring tension and engagement .of theV nob 22. If contact elements 63 are connected in an .ectric circuit then there will be established continuity etween the circuit of contact elements 65 and 68. Howver the circuit including wire 17 and contacts 60 will be solated from the circuits of contacts 66, 68 `since tip 20 a non-conductive member.

Since the shell 1S is under spring tension, the tubular in member 46 remains wholly concealed inside the shell utside of panel 54. If the pin 20 is disengaged by a pull xerted axially outward of head 1.2 or body l1, then the hell 1S will be automatically extended as the pin `cornes ut of hole 55. As a result the electrically conductive ubular member 46 is always concealed and shielded from xternal contact by an operator or any external circuit.

FIG. 5 shows the several parts in an exploded array. t will be noted these parts can easily be quickly asembled and disassembled for connecting and replacing vire i7 or for any other purpose.

FlGS. 6 and 7 show another plug lila which in side 'iew is identical to plug llt). This plug may be substiuted in place of plug for use with jack S5 of FIGS. 3 vnd 4.

In plug 16a, the body lla and head 12a are integrally ormed as a unit. Head 12a has an internal thread 70 tt the upper end of its central bore '72. An externally hreaded annular flange 74 at one end of the tubular ortion of insulated fitting 32 engages with thread 7i). [he tubular portion of the fitting has a diameter less than lange 74 and coil spring 49 is placed concentrically on vhis portion of the fitting as in plug 1d. The spring 49 )ears on the upper end of flange 19 of the shell l. The ipper end of the spring bears on the underside of flange 74. Pin 16a has a tubular conductive member 45 sup- ;orting non-conductive tip Zita which is integral with a ion-conductive axial stem 75. Stem 75 extends through 1he bore in tube 46 and out of head 44. The upper end 76 of the stem 75 is threaded and engages a nut 7S which holds a lug Sil on the end of the stem. The lug bears on the top of head 44. Cord 14 passes through hole 51B in flange 74. Wire 17 is crimped, soldered or otherwise secured to the lug. Thus electrical continuity is established and maintained between the wire and tubular member 46. Other parts of plug 16a corresponding to those of plug lil are identically numbered.

A pair of recesses S2 are formed in the outer end of the fitting for engagement by a suitable Spanner wrench used to remove and replace the fitting.

When the plug a is assembled it operates in the same manner as described for plug lf3. Shell i8 will retract when the pin la is advanced through a hole in a panel to engage a jack, as illustrated in FIG. 3.

In FIGS. 8 and 9, plug ltlb is similar to plug lil and corresponding pants are identically numbered. Plug ltib has a pin leb provided with an auxiliary contact ring 99 between knob 22 and tubular contact member 46. The ring 90 can be set into a circumferential groove 92 in the insulated tip 2Gb. Thus the exterior surface of the ring will be flush with the surface of non-conductive tip 2011 and member 46. A further groove 24a can be provided between knob 22 and member 46 in tip 2%.

The ring 9th serves to contact an additional pair of spring contacts 94 interposed in jack 55 just inside of contacts 69. The bent fingers 95 of another pair of spring contacts 96 just within contacts 94 engage in groove 24a. Contacts 65 engage in groove 24. The tip Zflb thus has a double knob construction with knobs 22 and 22 engaged by two pairs of contacts 66 and 9d. The arrangement of plug 10b yand jack 5S permits `a larger number of circuits to be opened or closed than is possible in jack 55, due to the larger number of contacts. In addition, lug 10b will be held more securely by jack 55 to the double knob engagement of the contacts.

Additional insulation strips or wafers 6l' are used to separate the added contacts 94, 96 from the adjacent ones and from each other.

In all forms of the invention, there is provided a plug structure in which a cylindrical body supports a fixed pin or prong in axial disposition therein. An axial movable shell shields electrically conductive parts of the pin in all positions of plug in engagement wi-th and out of engagement with a jack. The structure of plug 10a is somewhat simpler and uses less parts than plug 10. The parts of plug 1t) can be separated without use of any tool while plug 19a requires a wrench. The non-conductive pin 20a, with its non-conductive stem 75 employed in plug 10a, can be used in plug 16 in place of non-conductive tip Ztl with its short threaded stud 5t). Wire 17 will then be attached to the upper threaded end of stern '75 as illustrated in FIG. 6.

lt is also possible to employ non-conductive tip 20 in plug 19a in place of pin 20a and stem 75. Wire 17a will then be secured to tube 46 as shown in FIG. 4.

What is claimed and sought to be protected by Letters Patent of the United States is:

1. A plug for connecting an electric wire to an electric circuit having spaced pairs of spring contacts, comprising a generally cylindrical body, a pin supported in said body axially thereof, said pin having a non-conductive tip and a conductive portion adjoining said tip axially of the pin, a cylindrical shell supported by said body in axial alignment therewith, said pin extending axially out of one end -of said body, said shell being axially movable in said body and having a portion extending outwardly of said body, said portion of the shell surrounding at least part of said pin in all positions of said shell, spring means biasing said shell -outwardly of said body so that said conductive portion of the pin is wholly concealed and shielded by said shell when the shell is fully extended lfrom said body, said conductive portion ofthe pin being exposed when the shell is fully retracted into said body, a head at the other end of said body, an insulation fitting in said body, said fitting having a tubular portion carrying said spring 4means and detachably engaged with said conductive portion of the pin, -said fitting having a passage therethrough for receiving said electric wire, said conductiveportion of the pin having an end exposed in said fitting for connection of said wire thereto, said fitting having a flange at one end,

' said head being removably secured by threaded means on said body, and a ring engaged between said body and said head, said ring having a flange engaged with the flange of said fitting and holding said fitting and pin rigidly in axial alignment within said body.

2. A plug for connecting an electric wire to an electric circuit having spaced pairs of spring contacts, comprising a generally cylindrical body, a pin supported in said body axially thereof, lsaid pin having a non-conductive tip and a conductive portion adjoining said tip axially of the pin, a cylindrical shell supported by said body in axial alignment therewith, said pin extending axially out of one end of said body, said shell being axially movable in said body and having a portion extending outwardly of said body, said portion surrounding at least part of said pin in all positions of said shell, spring means biasing said shell outwardly of said body so that said conductive portion of the pin is wholly concealed and shielded by said shell when the shell is fully extended from said body, said conductive portion of the pin being exposed when the shell is fully retracted into said body, a head at the other end of said body, an insulation fitting in said body, said fitting having a tubular portion carrying said spring means and detachably engaged with said conductive portion of the pin, said litting having a passage therethrough for receiving said electric wire, said conductive portion of the pin having an end exposed in said tubular portion of the tting for connection of said wire thereto, said fitting having a flange at one end, and threaded means detachably holding said ange 4and head together, whereby said fitting and pin are held rigidly in axial alignment within said body.

3. A plug as claimed in claim 2 for connectingan electric Wire to an electric circuit having spaced pairs of spring contacts, wherein said non-conductive tip has a pair `of knobs at its free end and circumferential grooves at the knobs yfor separating and engaging two pairs of said contacts While another pair of said contacts engage said conductive portion of the pin, said pin having a conductiv element supported yon said tip and spaced from said con ductive portion for engaging a lfurther pair of said con aCtS.'

References Cited bythe Examiner UNITED STATES PATENTS 950,107 2/10 Larsson 339-183 1,324,278 12/'19 Scheel 339-182 l 1,526,265 2/25 Bergman 339-1-8l 2,082,986 6/37= Staley 3139-41 2,224,366 l2/40 Johnston 20D-51.01 2,253,593 10/41 Warren 339--4 2,338,141 1/44 Steckel 339-483 l 2,549,731 4/5'1= -Wattley 339-201 FOREIGN PATENTS 119,428 10/ 30 Austria.

20 ALBERT H. KAMPE, Primary Examiner.

JOSEPH D. SEERS, Examiner. 

2. A PLUG FOR CONNECTING AN ELECTRIC WIRE TO AN ELECTRIC CIRCUIT HAVING SPACED PAIRS OF SPRING CONTACTS, COMPRISING A GENERALLY CYLINDRICAL BODY, A PIN SUPPORTED IN SAID BODY AXIALLY THEREOF, SAID PIN HAVING A NON-CONDUCTIVE TIP AND A CYLINDRICAL SHELL SUPPORTED BY SAID BODY IN AXIAL ALIGNMENT THEREWITH, SAID PIN EXTENDING AXIALLY OUT OF ONE END OF SAID BODY, SAID SHELL BEING AXIALLY MOVABLE IN SAID BODY AND HAVING A PORTION EXTENDING OUTWARDLY OF SAID BODY, AND HAVING A PORTION EXTENDING OUTWARDLY OF SAID BODY, SAID PORTION SURROUNDING AT LEAST PART OF SAID PIN IN ALL POSITIONS OF SAID SHELL, SPRING MEANS BIASING SAID SHELL OUTWARDLY OF SAID BODY SO THAT SAID CONDUCTIVE PORTION OF THE PIN IS WHOLLY CONCEALED AND SHIELDED BY SAID SHELL WHEN THE SHELL IS FULLY EXTENDED FROM SAID BODY, SAID CONDUCTIVE PORTION OF THE PIN BEING EXPOSED WHEN THE SHELL IS FULLY RETRACTED INTO SAID BODY, A HEAD AT THE OTHER END OF SAID BODY, AN INSULATION FITTING IN SAID BODY, SAID FITTING HAVING A TUBULAR PORTION CARRYING SAID SPRING MEANS AND DETACHABLY ENGAGED WITH SAID CONDUCTIVE PORTION OF THE PIN, SAID FITTING HAVING A PASSAGE THERETHROUGH FOR RECEIVING SAID ELECTRIC WIRE, SAID CONDUCTIVE PORTION OF THE PIN HAVING AN END EXPOSED IN SAID TUBULAR PORTION OF THE FITTING FOR CONNECTION OF SAID WIRE THERETO, SAID FITTING HAVING A FLANGE AT ONE END, AND THREADED MEANS DETACHABLY HOLDIN SAID FLANGE AND HEAD TOGETHER, WHEREBY SAID FITTING AND PIN ARE HELD RIGIDLY IN AXIAL ALIGNMENT WITHIN SAID BODY. 